please could anybody be so kind and tell me if the following choice is a stupid one?

It's not stupid. But it may be viewed as unbalanced. Rather like buying a Formula 1 Sports car and fitting it with motorcycle tyres.

i have two reasons for it: one the small lens & its tiny adapters, second the price, i would get 4 different "lenses" for around $700 - and even a fisheye for an extra $ 120, in case i want it later on

this is the combination:

LUMIX® GH3

This is like a premium machine.

LUMIX® G X VARIO PZ 14-42mm / F3.5-5.6 ASPH. / POWER O.I.S. Lens

This is not the bestest lens that would suit such a premium machine. It works for sure and it's not bad, but it's not balanced in terms of perfomance.

These are front facing, add-on lenses. They are a way to give more features to that lens without paying a regular price for premium lenses. Because they are same brand and designed for that lens, I would not say your photo is very very bad but they are not a balanced way to get a very sharp or very aberration free photo.